1. Field of the Invention
The invention relates generally to apparatus for regulating the flow of solution from a reservoir into the vein of a patient and more particularly to solution flow regulating apparatus of the type which automatically maintains a constant rate of flow of solution into the vein of the patient and also shuts off the flow of solution into the patient's vein when the solution reservoir becomes empty to prevent the introduction of air.
2. Description of the Prior Art
U.S. Pat. No. 3,105,551, issued to Murphy, discloses an infusion safety valve which prevents the introduction of air into the patient's veins by means of an intravenous solution administering appartus. Murphy's invention comprises a bipartite chamber having inlet and discharge ports which are respectively adapted to be coupled to a solution reservoir and to the vein of the patient to whom the solution is being administered. The two chambers consist of an upper and a lower chamber. The lower chamber contains a float which has a piece of magnetic material mounted on its bottom. A piece of ferromagnetic material is mounted on the outside bottom surface of the lower chamber. When the solution contained within the lower chamber reaches a lower level, magnetic attraction between the float and the bottom of the chamber seats the float on the discharge port to prevent discharge of solution. Murphy, unlike the present invention, does not include any means contained within the fluid chamber for maintaining the flow of solution through the chamber at a constant rate independent of its initial height or variations in height of the solution level contained within the reservoir during depletion thereof. Additionally, Murphy's float does not regulate the upper level of solution which may be contained within the fluid chamber.
U.S. Pat. No. 2,844,147 issued to Beacham, U.S. Pat. No. 3,216,419, issued to Scislowicz, and U.S. Pat. No. 3,656,505 issued to O'Brian, each disclose an apparatus disposed within a drip chamber which is part of an intravenous feeding apparatus that prevents the introduction of air into the vein of the patient. Each of these devices utilizes a float-type device which functions as a valve to prevent the discharge of solution from the drip chamber when the level of solution contained therein becomes sufficiently low so that there is a danger of air being introduced into the vein of the patient through the drip chamber. Each of these devices differs substantially from the present invention in that the respective floats do not maintain a constant rate of flow of solution through the drip chamber independent of its initial height or variations in height of the solution reservoir; nor do they maintain the level of solution in the drip chamber between a lower and an upper level.